1. Field of the Invention
The present invention relates to a method for the non-invasive and simultaneous measurement of viscosity and temperature in very hot liquids (melts) such as polymers, metals, and glass at temperatures ranging from 200.degree. C.-3000.degree. C.
2. Discussion of the Background
Methods for measuring viscosity in liquids are known. Current methods employed for process control, at very high temperatures, infer viscosity from a temperature measurement. This assumes a predetermined relationship between viscosity and temperature. Any slight change in composition, and/or errors in temperature measurement leads to significant errors in viscosity measurement. There are no sensors currently available for measurement of the on-line (in-situ) viscosity measurement for melts at very high temperatures (above 1000.degree. C.). There are no sensors currently available which simultaneously measure temperature and viscosity. However, temperature measurement at high temperature is available using thermocouples. Current methods for measuring temperatures using immersed thermocouples are not desirable due to frequent breakage and inconsistent readings. Moreover, most high temperature applications require probes to be thermally conductive. This leads to a significant heat loss and cooling of molten metal at the probe/melt interface, or in other words, development of a "heat sink."
In view of the aforementioned deficiencies attendant with the prior art methods of measuring the viscosity of very hot liquids, it is clear that there exists a need in the art for an apparatus and method for performing such measurements, which methods avoid a "heat sink."